EP4242514A1 - Backlight module and display apparatus - Google Patents

Backlight module and display apparatus Download PDF

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Publication number
EP4242514A1
EP4242514A1 EP23161200.3A EP23161200A EP4242514A1 EP 4242514 A1 EP4242514 A1 EP 4242514A1 EP 23161200 A EP23161200 A EP 23161200A EP 4242514 A1 EP4242514 A1 EP 4242514A1
Authority
EP
European Patent Office
Prior art keywords
light
guide plate
light guide
disposed
backlight module
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP23161200.3A
Other languages
German (de)
English (en)
French (fr)
Inventor
Tzeng-Ke Shiau
Shih-Yen Cheng
Jung-Wei Chang
Chun-Wei Lee
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Coretronic Corp
Original Assignee
Coretronic Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Coretronic Corp filed Critical Coretronic Corp
Publication of EP4242514A1 publication Critical patent/EP4242514A1/en
Pending legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0075—Arrangements of multiple light guides
    • G02B6/0076—Stacked arrangements of multiple light guides of the same or different cross-sectional area
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133603—Direct backlight with LEDs
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0038—Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0053—Prismatic sheet or layer; Brightness enhancement element, sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0066—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide
    • G02B6/0068—Arrangements of plural sources, e.g. multi-colour light sources
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0081—Mechanical or electrical aspects of the light guide and light source in the lighting device peculiar to the adaptation to planar light guides, e.g. concerning packaging
    • G02B6/0086—Positioning aspects
    • G02B6/0088—Positioning aspects of the light guide or other optical sheets in the package
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0081—Mechanical or electrical aspects of the light guide and light source in the lighting device peculiar to the adaptation to planar light guides, e.g. concerning packaging
    • G02B6/0086—Positioning aspects
    • G02B6/0091—Positioning aspects of the light source relative to the light guide
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133606—Direct backlight including a specially adapted diffusing, scattering or light controlling members
    • G02F1/133607—Direct backlight including a specially adapted diffusing, scattering or light controlling members the light controlling member including light directing or refracting elements, e.g. prisms or lenses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0051—Diffusing sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0055—Reflecting element, sheet or layer

Definitions

  • the disclosure relates to a backlight module and a display apparatus, and in particular, to a backlight module and a display apparatus with two light guide plates.
  • a display apparatus in order to allow multiple viewers to watch together, a display apparatus usually has a display effect of a wide viewing angle.
  • the display effect of the wide viewing angle is likely to cause the screen to be peeped by others, resulting in leakage of confidential information.
  • the general practice is to place a light control film (LCF) in front of the display panel to filter out large-angle light.
  • an electronically controlled diffusion film may further be disposed above the LCF.
  • the electronically controlled diffusion film is controlled in a scattering state, so that the small-angle light from the LCF can be dispersed to a larger viewing angle range through the scattering of the electronically controlled diffusion film.
  • such an approach will cause the light energy of the light source not to be effectively utilized. Therefore, how to develop a display apparatus with extremely convenient viewing angle switching and better light energy utilization rates of the backlight module has become an important subject for related manufacturers.
  • the object is to provide a backlight module, which has a better light energy utilization rate.
  • the object is to provide a display apparatus, which has better light energy utilization rates in both a sharing mode and a privacy protection mode.
  • the backlight module includes a first light guide plate, a first light source, a diffusor, a second light guide plate, a second light source, a viewing angle control film, and a first prism sheet.
  • the first light guide plate has a first light incident surface, a first bottom surface, and a first light emitting surface. The first bottom surface and the first light emitting surface are connected to the first light incident surface and opposite to each other.
  • the first light source is disposed on one side of the first light incident surface of the first light guide plate.
  • the diffusor is disposed on one side of the first light emitting surface of the first light guide plate.
  • the second light guide plate is disposed on one side of the first bottom surface of the first light guide plate.
  • the second light guide plate has a second light incident surface, a second bottom surface, and a second light emitting surface.
  • the second bottom surface and the second light emitting surface are connected to the second light incident surface and opposite to each other.
  • the second light emitting surface faces the first bottom surface.
  • the second light source is disposed on one side of the second light incident surface of the second light guide plate.
  • the viewing angle control film is disposed between the first light guide plate and the second light guide plate.
  • the first prism sheet is disposed between the viewing angle control film and the first light guide plate.
  • an electronically controlled diffusion film may be disposed on one side of the first light emitting surface of the first light guide plate.
  • the electronically controlled diffusion film may be adapted to switch operation between a scattering state and a transparent state.
  • the diffusor may be located between the first light guide plate and the electronically controlled diffusion film.
  • a haze value of the diffusor may be in a range of greater than or equal to 10% to less than or equal to 95%.
  • the haze value of the diffusor may be in the range of greater than or equal to 25% and less than or equal to 75%.
  • the first light incident surface may be perpendicular to the second light incident surface.
  • the first prism sheet may have a first substrate and a plurality of first prism structures disposed on the first substrate.
  • an included angle between an extending direction of orthographic projection of each of the first prism structures on the first bottom surface and the first light incident surface may be greater than or equal to 60 degrees and less than or equal to 120 degrees.
  • the backlight module may further comprise a second prism sheet.
  • the second prism may be disposed between the viewing angle control film and the second light guide plate.
  • the second prism sheet may have a second substrate and a plurality of second prism structures disposed on the second substrate.
  • an included angle between an extending direction of orthographic projection of each of the second prism structures on the first substrate and the extending direction of the orthographic projection of each of the first prism structures on the first substrate may be less than or equal to 30 degrees.
  • the backlight module may further comprise a third prism sheet.
  • the third prism sheet may be disposed on one side of the first light emitting surface of the first light guide plate.
  • the third prism sheet may have a third substrate and a plurality of third prism structures disposed on the third substrate.
  • an included angle between an extending direction of orthographic projection of each of the third prism structures on the first light emitting surface and the first light incident surface may be less than or equal to 30 degrees.
  • the first light guide plate further may have a plurality of first optical microstructures disposed on the first bottom surface.
  • each of the first optical microstructures may have a first surface facing the first light source.
  • a first included angle between the first surface and the first bottom surface may be greater than or equal to 3 degrees and less than or equal to 60 degrees.
  • the second light guide plate may further have a plurality of second optical microstructures disposed on the second bottom surface.
  • each of the second optical microstructures may have a second surface facing the second light source.
  • a second included angle between the second surface and the second bottom surface may be greater than or equal to 3 degrees and less than or equal to 18 degrees.
  • the backlight module may further comprise a third light source.
  • the third light source may be disposed on one side of a third light incident surface of the first light guide plate.
  • the third light incident surface may be connected to the first light emitting surface and the first bottom surface.
  • the third light incident surface may be disposed opposite to the first light incident surface.
  • each of the first optical microstructures may further have a third surface facing the third light source.
  • a third included angle between the third surface and the first bottom surface may be greater than or equal to 3 degrees and less than or equal to 60 degrees.
  • the first light guide plate may further have a plurality of first columnar structures disposed on the first light emitting surface.
  • an extending direction of each of the first columnar structures may be perpendicular to the first light incident surface.
  • each of the first columnar structures may have a height along a normal direction of the first light emitting surface.
  • each of the first columnar structures may have a width along a direction perpendicular to the extending direction of each of the first columnar structures and parallel to the first light emitting surface ⁇
  • each of the first columnar structures may have a ratio of the height to the width of each of the first columnar structures is greater than or equal to 0.1.
  • the second light guide plate may further have a plurality of second columnar structures disposed on the second light emitting surface.
  • an extending direction of each of the second columnar structures may be perpendicular to the second light incident surface.
  • each of the second columnar structures may have a height along a normal direction of the second light emitting surface.
  • each of the second columnar structures may have a width along a direction perpendicular to the extending direction of each of the second columnar structures and parallel to the second light emitting surface.
  • each of the second columnar structures may have a ratio of the height to the width of each of the second columnar structures is greater than or equal to 0.1.
  • the backlight module may further comprise an electronically controlled viewing angle switch.
  • the electronically controlled viewing angle switch may be disposed on one side of the first light emitting surface of the first light guide plate.
  • the electronically controlled viewing angle switch may comprise a liquid crystal layer and at least two electrode layers disposed on opposite sides of the liquid crystal layer or at least one electrode layer disposed on one side of the liquid crystal layer.
  • the display apparatus includes a backlight module and a display panel.
  • the backlight module includes a first light guide plate, a first light source, a diffusor, a second light guide plate, a second light source, a viewing angle control film, and a first prism sheet.
  • the first light guide plate has a first light incident surface, a first bottom surface, and a first light emitting surface. The first bottom surface and the first light emitting surface are connected to the first light incident surface and opposite to each other.
  • the first light source is disposed on one side of the first light incident surface of the first light guide plate.
  • the diffusor is disposed on one side of the first light emitting surface of the first light guide plate.
  • the second light guide plate is disposed on one side of the first bottom surface of the first light guide plate.
  • the second light guide plate has a second light incident surface, a second bottom surface, and a second light emitting surface.
  • the second bottom surface and the second light emitting surface are connected to the second light incident surface and opposite to each other.
  • the second light emitting surface faces the first bottom surface.
  • the second light source is disposed on one side of the second light incident surface of the second light guide plate.
  • the viewing angle control film is disposed between the first light guide plate and the second light guide plate.
  • the first prism sheet is disposed between the viewing angle control film and the first light guide plate.
  • the display panel is disposed on one side of the first light emitting surface of the first light guide plate and overlaps the first light emitting surface and the second light emitting surface.
  • the backlight module may further comprises an electronically controlled diffusion film, disposed between the first light guide plate and the display panel, and adapted to switch operation between a scattering state and a transparent state.
  • the backlight module may further comprise an electronically controlled viewing angle switch, disposed between the first light guide plate and the display panel, and comprising a liquid crystal layer and at least two electrode layers disposed on opposite sides of the liquid crystal layer or at least one electrode layer disposed on one side of the liquid crystal layer.
  • an electronically controlled viewing angle switch disposed between the first light guide plate and the display panel, and comprising a liquid crystal layer and at least two electrode layers disposed on opposite sides of the liquid crystal layer or at least one electrode layer disposed on one side of the liquid crystal layer.
  • the first prism sheet is disposed between the first light guide plate and the second light guide plate which are disposed overlapping each other.
  • the first prism sheet can reflect part of the light emitted from the first bottom surface of the first light guide plate back to the first light guide plate, so as to increase the light energy utilization rate of the first light source.
  • the first prism sheet can further increase the light collection of the light from the second light guide plate, so as to improve the forward luminance of the display apparatus.
  • disposing the viewing angle control film between the two light guide plates may effectively reduce the risk that the light emitted by the first light source of the display apparatus is absorbed by the viewing angle control film when the display apparatus operates in the sharing mode, which helps to improve the light energy utilization rate of the backlight module.
  • FIGS. 1A and 1B are schematic side views of the display apparatus according to a first embodiment of the disclosure in different directions, respectively.
  • FIGS. 2, 3 , and 5 are schematic top views of some components of the display apparatus of FIG. 1A , respectively.
  • FIG. 4 is a schematic top view of another modified embodiment of some components of the display apparatus of FIG. 1A .
  • FIG. 6A is a schematic diagram illustrating the distribution of the brightness of light emitted by different light sources versus the viewing angle of the display apparatus operating in the sharing mode according to the first embodiment of the disclosure.
  • FIG. 6B is a schematic diagram illustrating the distribution of the total brightness versus the viewing angle of the display apparatus operating in the sharing mode according to the first embodiment of the disclosure.
  • FIG. 7 is a distribution curve diagram of the normalized brightness versus the viewing angle of the display apparatus operating in the sharing mode and the privacy protection mode according to the first embodiment of the disclosure.
  • a display apparatus 10 includes a backlight module 100 and a display panel 200 which are disposed in an overlapping manner.
  • the backlight module 100 includes a first light guide plate 110 and a second light guide plate 120 which are disposed in an overlapping manner.
  • the first light guide plate 110 is located between the display panel 200 and the second light guide plate 120.
  • the first light guide plate 110 has a first light incident surface 110is1, a first light emitting surface 110es, and a first bottom surface 110bs.
  • the first light emitting surface 110es and the first bottom surface 110bs are connected to the first light incident surface 110is1 and opposite to each other.
  • the display panel 200 is disposed on one side of the first light emitting surface 110es of the first light guide plate 110 and overlaps the first light emitting surface 110es.
  • the second light guide plate 120 is disposed on one side of the first bottom surface 110bs of the first light guide plate 110.
  • the display panel 200 is, for example, a liquid crystal display panel, or other non-self-luminous display panels.
  • the second light guide plate 120 has a second light incident surface 120is, a second light emitting surface 120es, and a second bottom surface 120bs.
  • the second light emitting surface 120es and the second bottom surface 120bs are connected to the second light incident surface 120is and opposite to each other.
  • the second light emitting surface 120es of the second light guide plate 120 faces the first bottom surface 1 10bs of the first light guide plate 110.
  • the display panel 200 overlaps the second light emitting surface 120es.
  • the first light guide plate 110 may further have a third light incident surface 110is2 connected to the first light emitting surface 110es and the first bottom surface 110bs and disposed opposite to the first light incident surface 110is 1, but is not limited thereto.
  • a first light source LS1 is disposed on one side of the first light incident surface 110is1 of the first light guide plate 110.
  • a second light source LS3 is disposed on one side of the second light incident surface 120is of the second light guide plate 120.
  • a third light source LS2 is disposed on one side of the third light incident surface 110is2 of the first light guide plate 110.
  • the first light incident surface 110is1 and the third light incident surface 110is2 of the first light guide plate 110 may be respectively perpendicular to the second light incident surface 120is of the second light guide plate 120 (as shown in FIG. 2 ), but are not limited thereto.
  • the first light source LS1, the third light source LS2, and the second light source LS3 are, for example, light bars composed of multiple light emitting elements (e.g., light emitting diodes) and circuit boards or cold cathode tubes, but are not limited thereto.
  • a reflective sheet 160 may further be disposed on one side of the second bottom surface 120bs of the second light guide plate 120.
  • the reflective sheet 160 is, for example, a silver reflective sheet, a white reflective sheet, or other suitable reflective sheets.
  • the backlight module 100 further includes a viewing angle control film 130, a first prism sheet 140, and a diffusor 170.
  • the viewing angle control film 130 is disposed between the first light guide plate 110 and the second light guide plate 120.
  • the first prism sheet 140 is disposed between the first light guide plate 110 and the viewing angle control film 130.
  • the diffusor 170 is disposed on one side of the first light emitting surface 110es of the first light guide plate 110, and is located between the first light guide plate 110 and the display panel 200.
  • the viewing angle control film 130 is, for example, a 3M's Louver film, Toray's PICASUS VT, or a polarized viewing angle control element.
  • the viewing angle control film 130 may define a viewing angle control direction VD of the display apparatus 10, and the viewing angle control direction VD is, for example, parallel to a direction X in FIG. 1A .
  • the viewing angle control film 130 may be disposed with multiple light-shielding walls 135, and the light-shielding walls 135 are arranged at intervals along the direction X and extend in a direction Y.
  • the light-shielding walls 135 are configured to at least partially reflect or absorb light, and light may pass between two adjacent of the light-shielding walls 135.
  • the first prism sheet 140 has a first substrate 141 and multiple first prism structures 142.
  • the first prism structures 142 are arranged along the direction Y on one side surface of the first substrate 141 facing the first light guide plate 110, and extend in the direction X.
  • an included angle A1 between the extending direction of the orthographic projection of the first prism structure 142 on the first bottom surface 110bs of the first light guide plate 110 and the first light incident surface 110is1 (or the third light incident surface 110is2) of the first light guide plate 110 may be 90 degrees (as shown in FIG. 3 ).
  • the included angle A1 may also be any angle other than 90 degrees within a range of greater than or equal to 60 degrees and less than or equal to 120 degrees.
  • the first light source LS1 and the third light source LS2 are adapted to emit light toward the first light guide plate 110, respectively.
  • Part of the light LB1 and LB2 is emitted from the first light emitting surface 110es after transmitted through the lateral direction of the first light guide plate 110, and is transmitted to the display panel 200.
  • another part of the light e.g., light LB1
  • the another part of the light is reflected or absorbed by the light-shielding walls 135 of the viewing angle control film 130, resulting in loss of light energy or formation of stray light.
  • the first prism sheet 140 Through the disposition of the above-mentioned first prism sheet 140, such unexpectedly emitted light (e.g., the light LB1”) can be reflected back to the first light guide plate 110, thereby increasing the light energy utilization rate of the light source.
  • the disposition of the first prism sheet 140 may further be configured to increase the light collection of the light LB3 after emitted from the second light guide plate 120, so as to improve the forward luminance of the display apparatus 10.
  • the backlight module 100 may further optionally include a second prism sheet 150, which is disposed between the viewing angle control film 130 and the second light guide plate 120. Similar to the first prism sheet 140, the second prism sheet 150 has a second substrate 151 and multiple second prism structures 152. The second prism structures 152 are arranged along the direction Y on one side surface of the second substrate 151 facing the first light guide plate 110, and extend in the direction X. That is, the extending direction of the orthographic projection of the second prism structure 152 on the first substrate 141 is substantially parallel to the extending direction of the orthographic projection of the first prism structure 142 on the first substrate 141.
  • the extending direction of the second prism structure 152 of the second prism sheet 150 is substantially parallel to the extending direction of the first prism structure 142 of the first prism sheet 140.
  • an included angle A2 between the extending direction of a second prism structure 152A of a second prism sheet 150A and the extending direction of the first prism structure 142 of the first prism sheet 140 may also be greater than 0 degrees and less than or equal to 30 degrees (as shown in FIG. 4 ).
  • Part of the light LB3 refracted twice through the first prism structure 142 and the second prism structure 152 may be transmitted to the first light guide plate 110 in a light path closer to the front view direction. Not only can the proportion of the light LB3 absorbed by the viewing angle control film 130 be reduced (i.e., an increase in the light energy utilization rate of the second light source LS3) after the light LB3 is emitted through the second light guide plate 120, but the concentration of light emitted through the second light guide plate 120 can further be improved.
  • the display apparatus 10 is adapted to operate in a sharing mode with a larger viewing angle range or a privacy protection mode with a smaller viewing angle range. It should be particularly noted that when the display apparatus 10 operates in the privacy protection mode, only the second light source LS3 provides the illumination light required for the privacy protection display. When the display apparatus 10 operates in the sharing mode, the first light source LS1, the third light source LS2, and the second light source LS3 provide the illumination light required for the wide viewing angle display.
  • first optical microstructures MS1 may further be disposed on the first bottom surface 110bs of the first light guide plate 110.
  • the first optical microstructure MS1 has a first surface RS1 facing the first light source LS1 and a third surface RS2 facing the third light source LS2.
  • the first surface RS1 is adapted to reflect the light LB1 from the first light source LS1 and transmitted in the first light guide plate 110, so that the light LB1 can be emitted from the first light guide plate 110 in a more positive light path.
  • the third surface RS2 is adapted to reflect the light LB2 from the third light source LS2 and transmitted in the first light guide plate 110, so that the light LB2 can be emitted from the first light guide plate 110 in a more positive light path (as shown in FIG. 1A ).
  • multiple second optical microstructures MS2 may further be disposed on the second bottom surface 120bs of the second light guide plate 120.
  • the second optical microstructure MS2 has a second surface RS3 facing the second light source LS3.
  • the second surface RS3 is adapted to reflect the light LB3 from the second light source LS3 and transmitted in the second light guide plate 120, so that the light LB3 can be emitted from the second light guide plate 120 in a more positive light path (as shown in FIG. 1B ).
  • a first included angle ⁇ 1 between the first surface RS1 of the first optical microstructure MS1 and the first bottom surface 110bs and a third included angle ⁇ 2 between the third surface RS2 and the third bottom surface 110bs may optionally be the same.
  • the first included angle ⁇ 1 and the third included angle ⁇ 2 are both greater than or equal to 3 degrees and less than or equal to 60 degrees.
  • a second included angle ⁇ 3 between the second surface RS3 of the second optical microstructure MS2 and the second bottom surface 120bs is greater than or equal to 3 degrees and less than or equal to 18 degrees.
  • the first included angle ⁇ 1 and the third included angle ⁇ 2 may be greater than or equal to 3 degrees and less than or equal to 30 degrees. Accordingly, the light LB1 from the first light source LS1 forms a light energy distribution of the viewing angle range biased to the right side (as shown by the curve C1a in FIG. 6A ) after reflected by the first surface RS1 of the first optical microstructure MS1.
  • the light LB2 from the third light source LS2 forms a light energy distribution of the viewing angle range biased to the left side (as shown by the curve C2a in FIG. 6A ) after reflected by the third surface RS2 of the first optical microstructure MS1.
  • the light LB3 from the second light source LS3 forms a light energy distribution of the front viewing angle range (as shown by the curve C3a in FIG. 6A ) after reflected by the second surface RS3 of the second optical microstructure MS2.
  • first columnar structures 115 may further be disposed on the light emitting surface 110es of the first light guide plate 110.
  • the first columnar structures 115 are arranged along the direction Y and extend in the direction X. More specifically, the extending direction of the first columnar structure 115 may be perpendicular to the first light incident surface 110is1 and the third light incident surface 110is2 of the first light guide plate 110 (as shown in FIG. 2 ).
  • the first columnar structure 115 has a height h1 along the normal direction (e.g., the direction Z) of the first light emitting surface 110es, and has a width w1 along a direction (e.g., the direction Y) perpendicular to the extending direction of the first columnar structure 115 and parallel to the first light emitting surface 110es.
  • the ratio of the height h1 to the width w1 of the first columnar structure 115 is greater than or equal to 0.1.
  • multiple second columnar structures 125 may further be disposed on the second light emitting surface 120es of the second light guide plate 120.
  • the second columnar structures 125 are arranged along the direction X and extend in the direction Y. More specifically, the extending direction of the second columnar structure 125 may be perpendicular to the second light incident surface 120is of the second light guide plate 120 (as shown in FIG. 2 ).
  • the second columnar structure 125 has a height h2 along the normal direction (e.g., the direction Z) of the second light emitting surface 120es, and has a width w2 along a direction (e.g., the direction X) perpendicular to the extending direction of the second columnar structure 125 and parallel to the second light emitting surface 120es.
  • the ratio of the height h2 to the width w2 of the second columnar structure 125 is greater than or equal to 0.1.
  • the backlight module 100 may be disposed on one side of the first light emitting surface 110es of the first light guide plate 110, and may further optionally be disposed with a third prism sheet 180 and an electronically controlled diffusion film 190.
  • the third prism sheet 180 is located between the electronically controlled diffusion film 190 and the first light guide plate 110, and the diffusor 170 is located between the first light guide plate 110 and the electronically controlled diffusion film 190.
  • the third prism sheet 180 has a third substrate 181 and multiple third prism structures 182.
  • the third prism structures 182 are arranged along the direction X on one side surface of the third substrate 181 away from the first light guide plate 110 and extend in the direction Y.
  • an included angle between the extending direction of the orthographic projection of the third prism structure 182 on the first light emitting surface 110es of the first light guide plate 110 and the first incident surface 110is1 (or the third incident surface 110is2) of the first light guide plate 110 is greater than 0 degrees and less than or equal to 30 degrees.
  • the extending direction of the orthographic projection of the third prism structure 182 on the first light emitting surface 110es of the first light guide plate 110 may optionally be parallel to the first incident surface 110is1 and the third incident surface 110is2 of the first light guide plate 110 (as shown in FIG. 5 ).
  • the electronically controlled diffusion film 190 is adapted to switch operation between the scattering state and the transparent state.
  • the scattering state of the electronically controlled diffusion film 190 may be used to expand the viewing angle distribution ranges of the light LB1, the light LB2, and the light LB3, so that the overall light type distribution of the light from different light sources may be more uniform (as shown in FIG. 6B ) after the light from different light sources are emitted from the first light guide plate 110.
  • the transparent state of the electronically controlled diffusion film 190 is used, so that the light LB3 from the second light source LS3 maintains the existing light type distribution after passing through the electronically controlled diffusion film 190.
  • the electronically controlled diffusion film 190 is, for example, a polymer dispersed liquid crystal (PDLC) film, a polymer network liquid crystal (PNLC) film, or a liquid crystal lens (LC Lens).
  • PDLC polymer dispersed liquid crystal
  • PNLC polymer network liquid crystal
  • LC Lens liquid crystal lens
  • the three light sources are used to emit light at the same time, and the configuration relationship of each of the above-mentioned film layer structures is used, so that the light energy distribution of these light sources disperse within different viewing angle ranges. Moreover, the overall light emitting brightness distribution is more uniform and the viewing angle range is wider through the scattering state of the electronically controlled diffusion film 190.
  • the display apparatus 10 operates in the privacy protection mode, only the second light source LS3 emits light, and the configuration relationship of each of the above-mentioned film layer structures is used, so that the light types of the emitted light concentrated within the front viewing angle range.
  • FIG. 8A is a schematic diagram illustrating the distribution of the brightness of light emitted by different light sources versus the viewing angle of the display apparatus operating in a sharing mode according to the another modified embodiment of FIG. 1A .
  • FIG. 8B is a schematic diagram illustrating the distribution of the total brightness versus the viewing angle of the display apparatus operating in the sharing mode according to the another modified embodiment of FIG. 1A . Different from the light energy distribution in FIG.
  • the light energy distribution of the light LB2 from the third light source LS2 is still biased to the left-side viewing angle, the light energy distribution of the light LB2 from the third light source LS2 is closer to the front viewing angle (as shown by the curve C2b in FIG. 8A ) after the light LB2 from the third light source LS2 is emitted through the first light guide plate 110.
  • the light emitting distributions of the first light source LS1 and the third light source LS2 on the first light emitting surface 1 10es of the first light guide plate 110 are closer to the light emitting distribution of the second light source LS3 on the first light emitting surface 1 10es of the first light guide plate 110 (as shown by the curve C3b in FIG. 8A ) when compared with FIG. 6A .
  • FIG. 8B shows the superimposed light types formed by the light of the above-mentioned light sources after scattered by the electronically controlled diffusion film 190.
  • the display apparatus may have higher brightness output in the front viewing angle range.
  • the selection of the diffusor 170 may be more flexible.
  • the haze value of the diffusor 170 is in the range of greater than or equal to 10% and less than or equal to 95%.
  • the haze value of the diffusor 170 is in the range of greater than or equal to 25% and less than or equal to 75%.
  • FIGS. 9A and 9B are schematic side views of the backlight module according to a second embodiment of the disclosure in different directions, respectively.
  • the difference between a backlight module 100A of the embodiment and the backlight module 100 of FIGS. 1A and 1B lies in that the backlight module 100A is not disposed with the third prism sheet 180 and the third light source LS2 of FIG. 1A .
  • a first optical microstructure MS1-A of a first light guide plate 110A of the embodiment has a first surface RS1 facing the first light source LS1 and a backlight surface BS farther away from the light source LS1, and the first surface RS1 and the backlight surface BS are disposed asymmetrically.
  • a first angle ⁇ 1' between the first surface RS1 of the first optical microstructure MS1-A and the first bottom surface 110bs is different from a fourth angle ⁇ 4 between the backlight surface BS and the first bottom surface 110bs.
  • the backlight module 100A may meet the lighting requirements of the asymmetric light type.
  • FIGS. 10A and 10B are schematic side views of the backlight module according to a third embodiment of the disclosure in different directions, respectively.
  • the difference between a backlight module 100B of the embodiment and the backlight module 100 of FIGS. 1A and 1B lies in that the backlight module 100B may not be disposed with the second prism sheet 150 and the third prism sheet 180 of FIG. 1A .
  • FIGS. 11A and 11B are schematic side views of the display apparatus according to the fourth embodiment of the disclosure in different directions, respectively.
  • FIG. 12 is a schematic cross-sectional view of the electronically controlled viewing angle switch of FIG. 11A .
  • FIG. 13 is a schematic diagram illustrating the distribution of the brightness versus the viewing angle of the display apparatus of FIG. 11A operating in different privacy protection modes. Referring to FIGS. 11A to 12 , the difference between a display apparatus 20 of the embodiment and the display apparatus 10 of FIG. 1A lies in that a backlight module 100C of the embodiment replaces the electronically controlled diffusion film 190 of the backlight module 100 in FIG. 1A with an electronically controlled viewing angle switch 195.
  • the electronically controlled viewing angle switch 195 may include a liquid crystal layer LCL, an electrode layer EL1, an electrode layer EL2, a substrate SUB1, a substrate SUB2, an alignment film AL1, an alignment film AL2, a polarizer POL1, and a polarizer POL2.
  • the liquid crystal layer LCL is disposed between the substrate SUB 1 and the substrate SUB2.
  • the electrode layer EL1 is disposed between the liquid crystal layer LCL and the substrate SUB 1.
  • the electrode layer EL2 is disposed between the liquid crystal layer LCL and the substrate SUB2.
  • the alignment film AL1 is disposed between the liquid crystal layer LCL and the electrode layer EL1.
  • the alignment film AL2 is disposed between the liquid crystal layer LCL and the electrode layer EL2.
  • the polarizer POL1 and the polarizer POL2 are respectively disposed on opposite sides of the substrate SUB1 and the substrate SUB2 away from the liquid crystal layer LCL.
  • the viewing angle control direction VD of the display apparatus 20 may be defined by the axial direction of the absorption axis of the polarizer POL2 that is closer to the display panel 200. That is, in the embodiment, the axial direction of the absorption axis of the polarizer POL2 is parallel to the direction X.
  • the alignment film is configured to align multiple liquid crystal molecules (not shown) of the liquid crystal layer LCL, so that the optical axes thereof are oriented in a predetermined direction.
  • the alignment directions of the two alignment films AL1 and AL2 may intersect with each other, for example, the angle between the two alignment directions may be in the range of 90 degrees to 270 degrees, and the liquid crystal layer LCL may include twisted nematic liquid crystal (TN-LC).
  • the electronically controlled viewing angle switch 195 of the embodiment may include a TN-LC cell or a super twisted nematic liquid crystal cell (STN-LC cell).
  • STN-LC cell super twisted nematic liquid crystal cell
  • the disclosure is not limited thereto.
  • the operation mode of the liquid crystal cell of the electronically controlled viewing angle switch may also be an electrically controlled birefringence (ECB) mode, an optically compensated bend (OCB) mode, an in-plane switching (IPS) mode, or a vertical alignment/multi domain vertical alignment (VA/MVA) mode.
  • EB electrically controlled birefringence
  • OOB optically compensated bend
  • IPS in-plane switching
  • VA/MVA vertical alignment/multi domain vertical alignment
  • the potential difference may form an electric field between the two electrode layers to drive the liquid crystal molecules of the liquid crystal layer LCL to rotate to change the overall phase retardation, thereby changing the polarization state of the light passing through the liquid crystal layer LCL.
  • the electrode layer EL1 and the electrode layer EL2 are, for example, light-transmitting electrodes, and the materials of the light-transmitting electrodes include indium tin oxide, indium zinc oxide, aluminum tin oxide, aluminum zinc oxide, or other suitable oxides, very thin metals, metal meshes or wire grids, carbon nanotubes, Ag nano-wires, graphene, or a stacked layer of at least two of the above.
  • the electrode layers of the electronically controlled viewing angle switch may be at least two electrode layers disposed on opposite sides of the liquid crystal layer according to different operation modes of the liquid crystal cell, or at least one electrode layer disposed on one side of the liquid crystal layer.
  • the display apparatus 20 may be further provided with different degrees of privacy protection effects through the disposition of the electronically controlled viewing angle switch 195.
  • a privacy protection display i.e., the second light source LS3 is enabled to emit light
  • the electronically controlled viewing angle switch 195 does not function, the display apparatus 20 operates in a first privacy protection mode, and has a first viewing angle range; if the electronically controlled viewing angle switch 195 is active, the display apparatus 20 operates in a second privacy protection mode, and has a second viewing angle range, and the second viewing angle range is smaller than the first viewing angle range.
  • the first prism sheet is disposed between the first light guide plate and the second light guide plate which are disposed overlapping each other.
  • the first prism sheet can reflect part of the light emitted from the first bottom surface of the first light guide plate back to the first light guide plate, so as to increase the light energy utilization rate of the first light source.
  • the first prism sheet can further increase the light collection of the light from the second light guide plate, so as to improve the forward luminance of the display apparatus.
  • disposing the viewing angle control film between the two light guide plates may effectively reduce the risk that the light emitted by the first light source of the display apparatus is absorbed by the viewing angle control film when the display apparatus operates in the sharing mode, which helps to improve the light energy utilization rate of the backlight module.
  • the term "the invention”, “the present invention” or the like does not necessarily limit the claim scope to a specific embodiment, and the reference to particularly preferred exemplary embodiments of the invention does not imply a limitation on the invention, and no such limitation is to be inferred.
  • the invention is limited only by the scope of the appended claims. Moreover, these claims may refer to use "first”, “second”, etc. following with noun or element. Such terms should be understood as a nomenclature and should not be construed as giving the limitation on the number of the elements modified by such nomenclature unless specific number has been given.
  • the abstract of the disclosure is provided to comply with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Planar Illumination Modules (AREA)
EP23161200.3A 2022-03-11 2023-03-10 Backlight module and display apparatus Pending EP4242514A1 (en)

Applications Claiming Priority (1)

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CN202220521242.5U CN216848405U (zh) 2022-03-11 2022-03-11 背光模块及显示装置

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TWI830253B (zh) * 2022-06-15 2024-01-21 誠屏科技股份有限公司 防窺顯示裝置及防窺方法

Citations (4)

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Publication number Priority date Publication date Assignee Title
US20080198295A1 (en) * 2007-02-19 2008-08-21 Mitsubishi Electric Corporation Backlight device and transmission type display apparatus
US20170153383A1 (en) * 2015-11-27 2017-06-01 Young Lighting Technology Inc. Backlight module, driving method thereof, and display apparatus using the backlight module
TWI725727B (zh) * 2020-02-05 2021-04-21 瑞儀光電股份有限公司 背光模組以及顯示器之視角調整方法
US20210191027A1 (en) * 2019-12-24 2021-06-24 Coretronic Corporation Backlight module and display apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080198295A1 (en) * 2007-02-19 2008-08-21 Mitsubishi Electric Corporation Backlight device and transmission type display apparatus
US20170153383A1 (en) * 2015-11-27 2017-06-01 Young Lighting Technology Inc. Backlight module, driving method thereof, and display apparatus using the backlight module
US20210191027A1 (en) * 2019-12-24 2021-06-24 Coretronic Corporation Backlight module and display apparatus
TWI725727B (zh) * 2020-02-05 2021-04-21 瑞儀光電股份有限公司 背光模組以及顯示器之視角調整方法

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